Aluminum alloys



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Patented Oct. 31, 1933 T OFFICE ,932,s ALUMINUM ALLOYS Robert '1. Wood,Cleveland, Ohio, minor to Aluminum Company Pa, a corporation ofPennsylvania application September 21,

No Drawing. Original 1932, Serial No. 634,15 plication November 645,114

This invention relates to aluminum base alloys containing magnesium. Theinvention has for its object the improvement of alloys of this class bythe addition thereto of about 0.05 to 2.0 per cent by weight of calcium.The invention is particularly concerned with the specificalloyshereinafter described.

The claim of this application coyers certain matter divided from mycopending application Serial No. 634,155 which is, in part, acontinuation of my cop'ending application Serial No. 595,231. Inventionsdisclosed but not claimed herein are claimed in my copen applicationsSerial Nos. 595,231, filed February 25, 1932, 545,108 to 645,113inclusive, and 545,115 to 645,125 inclusive, allfiled November 30, 1932.w

Considerable difllculty has heretofore been encountered in attempts tocommercially produce castings of aluminum case alloys containingsuicstantial amounts of magnesium. This dimculty is encountered both inthe making of sand castings and permanent mold or chill-mold castings,although the nature of the dimculty difiers somewhat in each case. Inthe case of sand castings there occurs a reaction between the moltenaluminum base alloy containing magnesium and the ordinary sand-moldmaterials, or vapors generated therefrom There is also a reaction withthe atmosphere. In addition, the magnesium-containing aluminum hasealloy does not new freely through narrow mold sections at an pouringtemperatures and, if the pouring temperature be raised, the solidifiedalloy is unsound. If the aluminum base alloy contaim'ng magnesium becast in a chill-mold the reaction sheet is 11.111 to some extent, butthe troubles from cold-shuts and mis-runs are accentuated because of themore rapid oi the molten metal. The considerations apply to the alumhose alloys specifically disclosed herein and particularly to suchalloys.

i have discovered that when calcium is added to alum base alloys of thetype and composition herein described, these culties are, to aoonshimahlev extent, F r ated. The calcium should he present in amountsranging from cos per cent to 2.0 per cent by weight subject to specificconsiderations as hereter disclosed.

In the melting oi aluminum alloys of the compositions herein described,a viscous scum often forms at the surface oi the molten metal. Failureof the molten metal to run properly through narrow mold a is caused, in

of America, Pittsburgh,

5. Divided and this ap- 30, 1932. Serial No.

part, by shreds-or particles of this scum being suspended in the moltenmetal and ofl'ering a resistance to the free passage of the metalthrough the apertures. Regardless of the cause of this low fluidity, Ihave discovered that the addition to the alloy of relatively smallamounts of calcium, in the preferred range between 0.05 to 0.5 per cent,improves the-casting characteristics to a very considerable extent andsimultaneously efiects a reduction of the scum or dross collecting at ornear the surface. In the casting of articles in sand molds, I prefer. toadd calcium in amounts less than about 0.5 per cent except in instanceswhere some reduction oi tensile strength or other mechanical or tensiloproperty is immaterial. In amounts of more than 0.5 per cent the calciumaddition produces the advantages enumerated herein hut has a tendency tolower some of the physical properties of the alloys. This ciiect is notharmful when calcium is present in amounts of ahout 0.5 per cent orless, but when high strength is not a desideratum the calcium may heused in amounts up to about 2.0 per cent. In intricate permanent moldcastings, where casting troubles are very serious if no calcium beadded, the improved physical properties obtained coincident with theproduction of good castings more than ofiset the ution in propertieswhich might otherwise result from the use of the calcium.

I have also discovered that when calcium is added to aluminum basealloys containing magnesium, the amount of gas evolved duringsolidihcation of the alloys is considerably reduced. When from about(limpet cent to 2.0 per cent by weight of calcium is added to thealloys, the amount of gas evolved becomes less marked with incr calciumcontent and the reduction of gas evolution may he so marked that themolten metal cools to the solidification temperature with a smoothmirror-like surface. I prefer to restrict the amount of calcium added toElinor cent or less since above this amount the physical properties ofthe alloys may he too seriously ailected. If the best physicalproperties are desired with an improved, although not complete, degreeof gas prevention, I keep the calcium content of the alloys between 0.05per cent and about 0.5 per cent.

In the application of the principles of invention I have determined thatce aluminum base alloys containing magnesium are :c ticularly benefitedthereby. For example, a very useful aluminum base alloy is onecontaining about 2.0 to 9.9 per cent of esium and cos Elli? per cent to2.0 per cent of calcium, as is alsoone of the class of metals heredefined as antimony and bismuth, such alloys being very useful where useat high temperatures is contemplated. Calcium may likewise be added toimprove such alloys when they contain, in addition to magnesium andantimony and/or bismuth, one or more of such alloying elements ascobalt, copper, nickel, manganese, zinc, etc. which may be added tomodify or produce a specific property in the alloy.

- The addition of 0.05 to 2.0 per cent of calcium is very beneficial inthe case of a series of alumimim base alloys which contain as majoralloying elements about 2.0 to 10.0 per cent of magnesium and about 0.2to 5.0 per cent of nickel. For instance, an aluminum base alloycontaining 3.0 to 7.5 per cent of magnesium and 0.2 to 2.0 per cent ofnickel is improved by the addition of 0.05 to 2.0 per cent of calcium asis, likewise, this same alloy when it also contains about 0.05 to 0.4per centof one or more of the class of elements composed of antimony andbismuth. Another excellent aluminum base alloy prepared in accordancewith the principles of my invention is one containing 3.0 to 8.0 per;posed of antimony and bismuth.

The principles of my invention find particular application in the caseof aluminum base alloys containing magnesium, nickel, and chromium andaluminum base alloys containing mangnesi um, nickel, and copper, as wellas those alloys containing magnesium, nickel, and cobalt. Examples maybe given of aluminum base alloys containing 2.0 to 10.0 per cent ofmagnesium, 0.2 to 5.0 per cent of nickel, 0.5 to 3.5 per cent ofchromium and 0.05 to 2.0 per cent of calcium. An aluminum base alloycontaining 3.0 to 8.0 per cent of magnesium, 0.5 to 3.5 per cent ofnickel, 0.5 to 3.5 per cent of chromium, and 0.05 to 2.0 per cent ofcalcium has excellent casting properties and the high temperatureproperties of this alloy can be favorably affected by the addition ofExamples may be given of aluminum base alloy containing 2.0 to 10.0 percent of magnesium, 0.2 to 5.0 per cent of nickel, 1.0 to 6.0 per cent ofcopper, and 0.05 to 2.0 per cent of calcium. An excellent alloy of thistype is one containing 3.0 to 8.0 per cent of magnesium, 0.5 to 5.0 percent of nickel, 1.0 to 6.0 per cent of copper, and 0.05 to 2.0 per centof calcium with or without 0.05 to 0.4 per cent of at least one of theclass of elements composed of antimony and bismuth and with or withoutthefurther addition of 0.5 to 3.5 per cent of at least one of a class ofelements composed of cobalt and chromium, and with or without thefurther addition of 0.1 to 1.0 per cent of at least one of a class ofelements composed of tungsten, vanadium, molybdenum, titanium, andzirconium.

Other excellent alloys are those aluminum base alloys containing about2.0 to 10.0 per cent 7 magnesium, 0.2 to 5.0 per cent nickel, 0.1 to 3.5per cent cobalt, and 0.05 to 2.0 per cent of calcium. A particularexample of this class of alloys, which may also contain withconsiderable advantage 0.05 to 0.4 per cent of a class'of elementscomposed of antimony and bismuth, is the aluminum base alloy containing3.0 to 8.0 per cent magnesium, 0.5 to 4.0 per cent nickel, 0.1 to 3.0per cent cobalt, and 0.05 to 2.0 per cent calcium.

Among other magnesium-containing aluminum base alloys which I have foundto be particularly benefited by the presence of calcium are numbered thealuminum base alloys containing 3.0 to 8.0 per cent of magnesium, 1.0 to6.0 per cent of copper, 0.5 to 3.5 per cent of chromium, and 0.05 to 2.0per cent of calcium, with or without the addition of 0.05 to 0.4 percent of at least one of a class of metals composed of antimony andbismuth and with or without the addition of other alloying elements.

The alloys herein described may be produced by the usual methods ofalloying metals. The calcium is preferably added to the molten alloy bythrusting the calcium beneath the surface with tongs or other suitableinstrument. The 120 aluminum used in preparing the alloys may be pure orit may contain the impurities found in commercial grades of this metal.Ordinarily a good commercial grade of virgin alminum'will give excellentresults and is preferable.

Having thus explained and described my invention, I claim:

A metallic alloy consisting of 3.0 to 8.0 per cent by weight ofmagnesium, 0.5 to 3.5 per cent by weight of nickel, 0.5 to 3.5 percentby weight 13 of chromium, 0.05 to 0.4 per cent by weight of at least oneof a class of elements composed of antimony and bismuth, and 0.05 to 2.0per cent by weight of calcium, the balance being aluminum.

ROBERT T. WOOD.

